The values in init_tss.ist[] can change when an IST event occurs.  Save
the original IST values for checking stack addresses when debugging or
doing stack traces.
Signed-off-by: NKeith Owens <kaos@ocs.com.au>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>